Zika Virus and Guillain Barré Syndrome: What’s the Latest?
Concerns over the Zika virus are escalating, especially as new cases quickly spread around the world. In fact, the World Health Organization (WHO) has officially declared the Zika virus a Public Health Emergency of International Concern. Transmission of the Zika virus has been documented in more than 67 countries and territories, and as of March 2017, there have been at least 5,139 confirmed cases in the United States, most of which were believed to be acquired during travel.
Although the Zika virus – which is spread to people primarily through a bite from an infected Aedes species mosquito – typically only results in mild illness, it may carry devastating consequences for some people.
Most widely reported has been the surge in cases of microcephaly among babies born to women who contracted the virus during pregnancy. This finding has prompted widespread travel restrictions for pregnant women. Microcephaly can restrict brain development, leading to abnormally small head size and severe brain damage. Data shows it is seen in as many as 13 percent of babies born to women infected with the Zika virus during pregnancy, according to a study published in the New England Journal of Medicine.
Is there a link between Zika and Guillain Barré syndrome?
As the Zika virus continues to take the world’s stage as an emerging public health threat, there is growing evidence that this mosquito-borne infection may also trigger Guillain Barré syndrome (GBS). GBS is a rare condition in which the immune system attacks the peripheral nervous system. For some, GBS can be quite serious, causing muscle weakness, sensory problems, pain and sometimes, paralysis. Many people need intensive medical care.
Because of the sharp rise in GBS cases seen in many regions where Zika outbreaks began, international researchers are hard at work, trying to understand the relationship between the two conditions. It seems there is something to it. Mounting evidence showing that as Zika virus cases spike, there seems to be a dramatic rise in cases of GBS have led some health officials to suggest that watching for increases in GBS may be one way to identify outbreaks of the Zika virus.
Researchers are closely following and mapping patterns of Zika virus and Guillain Barré syndrome.
- Twenty countries or territories have reported an increased number of GBS and/or laboratory confirmation of a Zika virus infection among people with GBS, according to the WHO.
See Zika Virus, Microcephaly and Guillain-Barre Syndrome, WHO Report at http://apps.who.int/iris/bitstream/10665/252650/1/zikasitrep22Dec2016-eng.pdf
- A report in the New England Journal of Medicine provides additional evidence of a connection, showing that GBS is occurring much more frequently than usual in at least seven countries and territories reporting Zika virus outbreaks. According to the analysis, GBS cases are at least double what they had been, and in some cases may be nearly 10 times higher, “imposing a substantial burden on populations and services in this region.” In Venezeula, in particular, cases have climbed as much as 877 percent. What’s more, researchers found that as Zika cases began to slow, GBS cases also began to wane. The study used data from 164,237 people with confirmed and suspected Zika infections and 1,474 people with GBS to investigate patterns between these diseases.
- A study by the U.S. Centers for Disease Control and Prevention (CDC) of 41 people in Brazil who developed GBS found that nearly all of them (90 percent) reported being acutely ill earlier with symptoms common to the Zika virus. Researchers are awaiting blood tests to confirm whether these people had, in fact, been infected by Zika.
- In another small study, researchers analyzed blood samples of patients diagnosed with GBS during the 2013 and 2014 Zika outbreaks in French Polynesia and found a 20-fold increase in GBS. Patients experienced symptoms of Zika virus infection on average six days before any neurological symptoms, and all of them carried Zika virus antibodies.
- The Puerto Rico Department of Health, with the help of the CDC, launched a GBS Passive Surveillance System to help identify new cases of GBS. Of 56 people with suspected cases of GBS who had an onset of neurological symptoms between January and July of 2016, nearly 2 out of 3 had evidence of Zika or flavivirus. Most patients reported having an acute illness before the onset of these symptoms, which only took an average of 5 days to develop.
Taken together, these studies raise concerns that Zika may cause GBS, which can have devastating and long-lasting effects. Still, more research is needed. The CDC is continuing to investigate the link between Zika and GBS.
GBS can be triggered by a variety of infections, including dengue, chikungunya viruses. Experts believe a similar pattern is at work with the Zika virus. The thought is that the body creates antibodies to marshal an assault on the Zika infection, and after the illness subsides, these antibodies then start attacking the peripheral nerves that connect the brain and spinal cord to the rest of the body. According to the CDC, “clusters” of cases of GBS are very unusual.
- Geographic distribution of the Zika virus is steadily widening.
- It’s a hard virus to predict.
- There remain many questions about Zika’s transmission and its relationship to other serious conditions, including GBS.
- There is no vaccine, and recent reports raise concerns about whether a vaccine might inadvertently incite more cases of GBS.
Researchers caution that there is still a lot we don't know about the Zika virus and how it might affect the immune system.
There is growing concern over whether the Zika virus can also trigger GBS, which can lead to paralysis and the need for specialized rehabilitation services like those available at Shepherd Center.
Download a PDF of our Guillain Barré syndrome fact sheet here.